82 lines
2.4 KiB
Rust
82 lines
2.4 KiB
Rust
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use crate::mem::paging::EntryFlags;
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use crate::mem::FrameAllocator;
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use super::tables::{Level1, Table};
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use super::{ActivePageTable, VirtualAddress, Frame};
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use super::Page;
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pub struct TemporaryPage {
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page: Page,
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allocator: TinyAllocator
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}
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struct TinyAllocator([Option<Frame>; 3]);
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impl TemporaryPage {
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pub fn new<A>(page: Page, allocator: &mut A) -> TemporaryPage
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where A: FrameAllocator
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{
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TemporaryPage {
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page: page,
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allocator: TinyAllocator::new(allocator),
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}
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}
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/// Maps the temporary page to the given frame in the active table.
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/// Returns the start address of the temporary page.
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pub fn map(&mut self, frame: Frame, active_table: &mut ActivePageTable)
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-> VirtualAddress
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{
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assert!(active_table.translate_page(self.page).is_none(),
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"temporary page is already mapped");
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active_table.map_to(self.page, frame, EntryFlags::WRITABLE, &mut self.allocator);
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self.page.start_address()
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}
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/// Unmaps the temporary page in the active table.
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pub fn unmap(&mut self, active_table: &mut ActivePageTable) {
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active_table.unmap(self.page, &mut self.allocator)
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}
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/// Maps the temporary page to the given page table frame in the active
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/// table. Returns a reference to the now mapped table.
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pub fn map_table_frame(&mut self,
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frame: Frame,
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active_table: &mut ActivePageTable)
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-> &mut Table<Level1> {
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unsafe { &mut *(self.map(frame, active_table) as *mut Table<Level1>) }
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}
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}
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impl FrameAllocator for TinyAllocator {
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fn allocate_frame(&mut self) -> Option<Frame> {
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for frame_option in &mut self.0 {
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if frame_option.is_some() {
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return frame_option.take();
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}
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}
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None
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}
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fn deallocate_frame(&mut self, frame: Frame) {
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for frame_option in &mut self.0 {
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if frame_option.is_none() {
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*frame_option = Some(frame);
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return;
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}
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}
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panic!("Tiny allocator can hold only 3 frames.");
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}
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}
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impl TinyAllocator {
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fn new<A>(allocator: &mut A) -> TinyAllocator
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where A: FrameAllocator
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{
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let mut f = || allocator.allocate_frame();
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let frames = [f(), f(), f()];
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TinyAllocator(frames)
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}
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}
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